1. Field of the Invention
This invention relates to an anti-skid brake system for a vehicle.
2. Description of the Prior Art
In an anti-skid brake system for a vehicle, the braking pressures applied to the wheels of the vehicle in response to depression of the brake pedal are controlled so that the wheel speeds are reduced at a target deceleration or at a target slip ratio, thereby preventing lock and skid of the wheels and stopping the vehicle in a short distance with a directional stability.
There have been proposed various anti-skid brake systems. For example, in the anti-skid brake system disclosed in Japanese Unexamined Patent Publication No. 60(1985)-1061, the braking pressures are reduced as the steering angle increases, thereby improving both the braking efficiency and the driving stability.
When the brake pedal is pushed down while the steering wheel is being turned, the rear wheels can skid to make the vehicle spin. When the vehicle spins, the wheel speeds lower at relatively large deceleration rates. Since the anti-skid brake system is generally arranged to control the braking pressure applied to each wheel so that the deceleration rate of the wheel speed is, for instance, in the range of 0.3 G to 1.0 G in order to prevent lock of the wheel, the braking pressure is reduced when the deceleration rate of the wheel speed is larger than the range.
Even after the spin of the vehicle ends and the vehicle begins to run straight ahead, the wheel speed keeps low relative to a pseudo vehicle speed on the basis of which whether the wheel tends lock is determined, and the braking pressure is kept reduced or fixed. Accordingly, the vehicle keeps running for a while after it begins to run straight ahead.